New scientific paper on assessment of PFAS contamination in soil

Eurofins has together with researchers from Örebro University, Sellén & Filipovic, Tongji University (Shanghai) and City University of Hong Kong published a new article in the journal Environmental Science & Technology that addresses analytical methods for assessment of PFAS contamination by the use of fire fighting foams. The research was financially supported by Eurofins.

The use of aqueous film-forming foams (AFFF) has led to widespread soil contamination with PFAS. Soil that has been contaminated can act as a long-term source and consequently lead to pollution of ground- and surface water. Development and comparison of analytical methods to assess the “total” content of PFAS is thus of importance. Different soil extractions can also be a relevant factor. In turn, the amounts and composition of PFAS in soil can be of great value in the risk assessment of the site.

Ten soil samples from three AFFF polluted sites in Sweden were analyzed. Soils were extracted by alkaline methanol followed by acidic methanol. The two fractions were analyzed separately by target analysis, suspect screening (incl semi-quantification) and EOF (extractable organic fluorine). In total 36 PFAS were identified with suspect screening. In eight of ten soils >80% of the EOF was found in the initial alkaline extract. Average fractions of zwitterionic and cationic PFAS found in the acidic extract ranged from 10-35% and no compound was unique to this fraction. At the same time >95% of the anionic PFAS were observed in the alkaline extract. The percentage of EOF explained by target PFAS varied between 1 to 79% with the highest numbers calculated for soils dominated by PFOS. If semi-quantified concentrations of PFAS found at suspect screening were added, the degree of EOF explained increased but in the majority of soils, there was still a large unknown part.

The 36 PFAS detected during suspect screening covered different fluorotelomer (FT) and sulphonamide (SA) precursors as well as PFSA (perfluorinated sulphonic acids) derivatives. The major FT precursor was 6:2 FTAB which was found at all sites but also higher analogues such as 8:2 and 10:2 were determined at two. 6:2 FTSHA-sulfoxide is another 6:2 substance that merits further attention. Among important SA precursors N-TAmP-N-FHxSA and -FOSA (C6 and C8) can be mentioned. Regarding PFSA derivatives F5S-PFOS was the most significant and identified at all sites, but also ketone-, chloro-, hydro- and ether PFSA could be observed. 

The work has given valuable insights into the occurrence and distribution of AFFF related PFAS in contaminated soil and has facilitated construction of fluorine budgets as well as comparisons between various analytical methods. The experience from the results and approach of the study has been valuable in development work at the Eurofins PFAS competence centre, for example when performing suspect screenings.   

A link to the open access paper can be found at our publication page

If you have any questions concerning the work please contact the co-authors:

Patrick van Hees, e-mail: patrick.vanhees@ftn.eurofins.com

Patrik Karlsson, e-mail: patrik.karlsson@ftn.eurofins.com